In a spin-transfer-torque MRAM, a magnetoresistive effect element using a perpendicular magnetic film is effective for reducing a write current and increasing the capacity of the memory.
In the magnetoresistive effect element used in the spin-transfer-torque MRAM, a material of a perpendicular magnetic film used in a reference layer is preferably a material which can be designed to reduce saturation magnetization of a reference layer in view of shift adjustment of the switching field of the storage layer.
For example, in an amorphous TbCoFe film, the saturation magnetization of the magnetic film can be changed by adjusting a composition ratio between Tb and CoFe. Therefore, the amorphous TbCoFe film is a promising material as a reference layer of a perpendicular magnetic film.
However, the amorphous TbCoFe film has a low level of heat resistance in perpendicular magnetic anisotropy. For this reason, heat treatment for crystallizing a member of a magnetoresistive effect element (such as a tunnel barrier layer) cannot be executed with a sufficient amount of heat (heating temperature). Therefore, it used to be difficult to improve element characteristics of the magnetoresistive effect element using the amorphous TbCoFe film.